Linda Gask1 and Carolyn Chew-Graham2
1 University of Manchester, Manchester, UK
2 Research Institute, Primary Care and Health Sciences and National School for Primary Care Research, Keele University, Keele, UK
Anxiety and depression are both common mental health disorders. They are the commonest mental health problems in the community, and the great majority of people who experience these problems will be treated in primary care.
In the UK, primary care services are an integral part of the National Health Service (NHS) in which general practitioners (GPs) work as independent contractors. The GP works as a generalist and a provider of personal, primary and continuing care to individuals, families and a practice population, irrespective of age, gender, ethnicity and problems presented.
In this book we will consider both depression and anxiety with reference to specific case histories: the O’Sullivan family and their neighbours (see Box 1.1). We will be adopting a life cycle perspective, considering depression and anxiety at different ages and times of life and in different settings although primarily taking a primary care perspective.
Some people may describe themselves as ‘depressed’ when they are unhappy. ‘Depression’ is more than unhappiness: A person who is depressed will experience low mood, which is lower than simply being ‘sad’ or ‘unhappy’, and crucially is associated with difficulty in being able to function as effectively as is usual for them in their everyday life. The severity of this mood disturbance can vary between a mild degree of difference from the norm, through moderate levels of depression to severe depression, which may be then associated with abnormal or ‘psychotic’ experiences such as delusions and hallucinations. Low mood is accompanied by a wide range of other symptoms, which also need to be present in order to make the diagnosis of depression (see diagnostic criteria, Appendix 2). In bipolar disorder, episodes of depression and mania are both experienced. We will not be focusing specifically on bipolar disorder in this book but will highlight how, where and why it is important to distinguish bipolar from unipolar depression.
Similarly, ‘anxiety’ is a term in common usage to describe feeling worried and fearful. People who are suffering with one or more of the anxiety disorders also experience symptoms of anxiety to a degree that it interferes with their ability to function. The central emotions at the heart of anxiety are fear and worry. You may be worried and fearful because you feel unsafe and have a sense of foreboding and uncertainty, as in generalised anxiety, or you may have a specific fear or phobia, or experience sudden crescendos of anxiety associated with physical symptoms, which are known as panic. Obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD) are also included among the anxiety disorders (see Box 1.2).
Although they have traditionally been classified as separate disorders, there is a considerable overlap between anxiety and depression. The majority of people who are seen in primary care settings will have a mixture of symptoms of anxiety (with often symptoms of different anxiety disorders present) and depression, and often also physical symptoms that may be related to either or both of these, or for which there is no apparent physical cause (and also other health problems too). People with more severe disorders who are seen in specialist settings may have a more distinct presentation of depression or one of the anxiety disorders, but even here they often coexist (see both Maria’s and Francis’s stories in Box 1.3 and Chapter 2). Anxiety may precede the development of depression and vice versa. The coexistence of symptoms had led some to question whether these are indeed distinct disorders.
The two major diagnostic systems in use for mental disorders are the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM), which has recently been published in its fifth edition, and the International Classification of Diseases (now ICD-10 with edition 11 in preparation). These differ slightly in the criteria used for diagnosis of depressive and anxiety disorders. We will describe the specific symptoms associated with each way in which they can present across the life cycle in different chapters of this book.
There has been criticism about the applicability of diagnostic criteria developed in the population of people seen in specialist settings to the way in which anxiety and depression present in the wider community and in primary care. In general, presentations in primary care are less severe, though there is considerable overlap in terms of severity with those people who present to mental health services. Primary care patients frequently present a mixture of psychological, physical and social problems, and the context of life events and medical comorbidity plays an important role in how patients experience their mental health symptoms. What is clear is that overlapping degrees of psychopathology exist along a spectrum of anxiety, depression, somatisation and substance misuse. Thus, Francis (Boxes 1.1 and 1.3) has a number of problems including anxiety, depression and alcohol dependence. This coexistence may be cross-sectional in that all these symptoms appear together at the same time, or it may be longitudinal, as one set of symptoms is followed closely in time by another. All of these may occur against a background of personality difficulty or disorder. Physical health problems, especially long-term conditions such as diabetes, coronary heart disease, chronic obstructive pulmonary disease and pain (see Chapter 6) may be complicated by depression and anxiety, which will both exacerbate the distress, pain and disability associated with physical illness and adversely affect health outcomes.
Depression is a considerable contributor to the global burden of disease, and according to the World Health Organization unipolar depression alone (not associated with episodes of mania) will be the most important cause by 2030.
Estimates of prevalence vary considerably depending on the methods used to carry out the research, and the diagnostic criteria employed. In the UK the household survey of adult psychiatric morbidity in England carried out in 2007 found that 16.2% of adults aged 16 to 64 met diagnostic criteria for at least one of the common mental health disorders in the week prior to the interview. More than half of these presented with a mixed anxiety and depressive disorder (9% of the population in the last week). The 1-week prevalence for the other common mental health disorders were 4.4% for Generalised Anxiety Disorder (GAD), 2.3% for a depressive episode, 1.4% for phobia, 1.1% for Obsessive-Compulsive Disorder (OCD) and 1.1% for Panic Disorder.
Both anxiety and depression are more common in women, with a prevalence of depression around 1.5–2.5 times greater than in men. The gender difference is even greater in the South Asian population in the UK (see Chapter 8). Depression and anxiety occur in children and young people (Chapter 2), and are more common in older people than in adults of working age (Chapter 4). In the UK household survey, men and women who were married or widowed had the lowest rates of disorder, and those who were separated or divorced the highest rates. This is probably due to both the impact of separation or divorce on a person’s mental health and the impact of depression in one partner on relationships. For women, family and marital stresses may be a particularly common factor leading to the onset of mental health problems. Those living in the lowest income households in society are also more likely to have a common mental health disorder. The prevalence of depression in older people is thought to be up to 20%, and 25% in people who also have a long-term physical condition (Chapter 6).
The average age of a first episode of depression or anxiety is in the early to mid-20s, but this can occur at any time from childhood (see Chapter 2) to old age (Chapter 4). Research in this area is problematic because many people with symptoms of anxiety may not seek help. A person with obsessive-compulsive symptoms may take up to 15 years or longer to seek help. In general, the earlier problems are first experienced, the more likely they are to recur, and many people with anxiety and depression experience problems from their teenage years. Given that more than 50% of people with depression will have at least one further episode, and that for many it has a relapsing and remitting course throughout their lives, depression can itself be viewed as having many of the feature of a chronic illness, which has important implications for treatment and longer term management. Over time, symptoms may change in severity and in form, with more anxiety than depression or vice versa. Those people who experience symptoms of panic and agoraphobia are likely to have a chronic course, and fear and avoidance of situations in which panic might occur can lead to considerable disability and social isolation.
A combination of biological, social and psychological factors contribute to the onset of depression and anxiety. These interact with each other to differing degrees in each individual, and it is helpful to think in terms of ‘vulnerability’ and ‘resilience’ when considering the likelihood that a person will experience symptoms if they experience stress in their lives.
Within the O’Sullivan family (Box 1.1) there is a history of mental illness and, as a general rule, the more first-degree relatives who have suffered anxiety and/or depression, the more severe a person’s experience of illness will be. This will not solely be as a result of genetic factors.
Genetic factors are important, but there is no specific gene for ‘depression’ or ‘anxiety’. As well as influencing vulnerability, genes also control resilience – a low likelihood that a person will become depressed or anxious when under stress.
Early life experience increases our vulnerability, in particular maternal separation, maternal neglect and exposure to emotional, physical or sexual abuse. There is evidence that these early experiences may have biological effects – leading to hyper-responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis. Later, ageing with associated loss increases vulnerability to depression.
The major contributors are severe life events (see Maria’s story, Chapter 3), which are particularly likely to precipitate depression when combined with chronic social disadvantage or lack of support. Additionally, severe physical health problems can precipitate depression or anxiety, especially if it is life-threatening or causes disability. In key research carried out 30 years ago, George Brown and his colleagues demonstrated how life events were more likely to trigger depression in women living in Camberwell, south-east London, if they had three or more children under the age of 14 living at home, no paid employment outside the home and lacked a confiding relationship with another person. Financial problems, poor housing and social isolation are key stresses that can lead to the onset of symptoms.
Some social factors both trigger the onset of symptoms and delay recovery. Bereavement, particularly one that is complicated, as we will see in Chapter 7, can lead to prolonged symptoms of depression in some people. Separation and divorce, physical disability, prolonged unemployment and other life events that lead to the person experiencing a sense of being chronically ‘threatened’ or ‘trapped’, such as in a prolonged and difficult marital or family dispute, can all lead to a failure to recover. We know that females are more likely than males to experience onset of symptoms and are less likely to recover; women seem to experience a greater number of distressing life events and may feel trapped by difficult marital and family circumstances.
Freud’s theory of depression linked depression with the experience of loss and prolonged mourning. It can be helpful in understanding how prolonged grief develops into depression. One of the best known recent theories of depression is the cognitive theory proposed by Beck, from which cognitive-behavioural therapy has developed. In early life, in response to adverse events as described above, dysfunctional and quite rigid views of the self are developed (known as schemas). Life events that seem to particularly fit with these attitudes and beliefs will later trigger anxiety and/or depression. The content of these schemas is particularly negative in depression, with negative views about the self, the world and the future, such as ‘I will never be a success’, ‘No-one will ever like me.’ In anxiety, the belief will be concerned with threat, danger and vulnerability. Behavioural theories focus more on the way in which people who are depressed reduce their activity, stop doing things that are pleasurable, and become isolated, which further prolongs their depression. In behavioural activation the depressed person is encouraged to act better in order to begin to feel better.
The monoamine hypothesis of depression and anxiety proposes that mood disorders are caused by a deficiency of the neurotransmitters noradrenaline and serotonin at key receptor sites in the brain. The way in which most antidepressants work is by altering activity at these receptors. However, it is now clear that this is far from the whole story. Inflammatory mechanisms may also play a part in the onset and continuation of depression and alter the functioning of the HPA axis. Neuroimaging studies show a significant reduction in the volume of the hippocampus in depression, and changes in activity in several regions of the brain. How these biological factors contribute to or result from the impact of life events and experiences remains a subject of much research, but cognitive-behavioural therapy has been shown in neuroimaging studies to alter functioning in specific areas of the brain linked with anxiety and depression.
Primary care clinicians have an important role in the detection and management of anxiety and depression in patients consulting them. The importance of listening to the patient’s story and understanding the context in which people live, is vital when formulating the problem and negotiating management.